Hide the mouse when the user is typing in the editor (#25040)

Closes https://github.com/zed-industries/zed/issues/4461

This PR improves the coding experience by hiding the mouse while the
user is typing so it does not accidentally get in their way, making it
challenging to ready characters in the editor.

Release Notes:

- The following PR hides the cursor when the user is typing by adding a
new cursor style called `None`.
- Assuming the user does not move the mouse, it will stay hidden until
it is moved again.


https://github.com/user-attachments/assets/6ba9f2ee-b9f3-4595-81e4-e9d986da4a39

---------

Co-authored-by: Agus <agus@zed.dev>
Co-authored-by: Peter Tripp <peter@zed.dev>
Co-authored-by: Kirill Bulatov <kirill@zed.dev>

crates/gpui/src/platform/linux/platform.rs

@@ -666,6 +666,12 @@ impl CursorStyle {
             CursorStyle::DragLink => "alias",
             CursorStyle::DragCopy => "copy",
             CursorStyle::ContextualMenu => "context-menu",
+            CursorStyle::None => {
+                #[cfg(debug_assertions)]
+                panic!("CursorStyle::None should be handled separately in the client");
+                #[cfg(not(debug_assertions))]
+                "default"
+            }
         }
         .to_string()
     }

crates/gpui/src/platform/linux/wayland.rs

@@ -35,6 +35,12 @@ impl CursorStyle {
             CursorStyle::DragLink => Shape::Alias,
             CursorStyle::DragCopy => Shape::Copy,
             CursorStyle::ContextualMenu => Shape::ContextMenu,
+            CursorStyle::None => {
+                #[cfg(debug_assertions)]
+                panic!("CursorStyle::None should be handled separately in the client");
+                #[cfg(not(debug_assertions))]
+                Shape::Default
+            }
         }
     }
 }

crates/gpui/src/platform/linux/wayland/client.rs

@@ -667,7 +667,13 @@ impl LinuxClient for WaylandClient {
             let serial = state.serial_tracker.get(SerialKind::MouseEnter);
             state.cursor_style = Some(style);
 
-            if let Some(cursor_shape_device) = &state.cursor_shape_device {
+            if let CursorStyle::None = style {
+                let wl_pointer = state
+                    .wl_pointer
+                    .clone()
+                    .expect("window is focused by pointer");
+                wl_pointer.set_cursor(serial, None, 0, 0);
+            } else if let Some(cursor_shape_device) = &state.cursor_shape_device {
                 cursor_shape_device.set_shape(serial, style.to_shape());
             } else if let Some(focused_window) = &state.mouse_focused_window {
                 // cursor-shape-v1 isn't supported, set the cursor using a surface.

crates/gpui/src/platform/linux/x11/client.rs

@@ -1438,13 +1438,16 @@ impl LinuxClient for X11Client {
         let cursor = match state.cursor_cache.get(&style) {
             Some(cursor) => *cursor,
             None => {
-                let Some(cursor) = state
-                    .cursor_handle
-                    .load_cursor(&state.xcb_connection, &style.to_icon_name())
-                    .log_err()
-                else {
+                let Some(cursor) = (match style {
+                    CursorStyle::None => create_invisible_cursor(&state.xcb_connection).log_err(),
+                    _ => state
+                        .cursor_handle
+                        .load_cursor(&state.xcb_connection, &style.to_icon_name())
+                        .log_err(),
+                }) else {
                     return;
                 };
+
                 state.cursor_cache.insert(style, cursor);
                 cursor
             }
@@ -1938,3 +1941,19 @@ fn make_scroll_wheel_event(
         touch_phase: TouchPhase::default(),
     }
 }
+
+fn create_invisible_cursor(
+    connection: &XCBConnection,
+) -> anyhow::Result<crate::platform::linux::x11::client::xproto::Cursor> {
+    let empty_pixmap = connection.generate_id()?;
+    let root = connection.setup().roots[0].root;
+    connection.create_pixmap(1, empty_pixmap, root, 1, 1)?;
+
+    let cursor = connection.generate_id()?;
+    connection.create_cursor(cursor, empty_pixmap, empty_pixmap, 0, 0, 0, 0, 0, 0, 0, 0)?;
+
+    connection.free_pixmap(empty_pixmap)?;
+
+    connection.flush()?;
+    Ok(cursor)
+}